Lecture 22 Flashcards
Pathogenesis (32 cards)
pathogens
cause harm to their host - are parasitic
infection
the successful colonization of a host by a (pathogenic) microorganism
primary pathogen
always harmful
ex. certain strands of e. coli (ehec - shiga toxin producing e. coli)
opportunist pathogen
context-dependent
open wound, compromised immune system
communicable vs non-communicable disease
contagious vs not
stages of infection
exposure,
adherence (skin or mucosa),
invasion
colonization and growth
toxicity / invasiveness
tissue damage… disease
nosocomial infection
acquired in a hospital
iatrogenic infection
transmitted by healthcare workers
are all diseases caused by pathogens?
no! ex. sickle cell disease : noninfectious genetic disorder
spectrum of virulence (1-10)
“norovirus”
highly virulent
ID50
measure for spectrum of virulence
“infectious dose in 50% of subjects” … # of pathogen particles needed to cause active infection in 50% of subjects.
LD50
lethal dose 50
how likely is a microbe to be pathogenic
1 in a billion !
how do pathogens view hosts
as nutrient source, shelter
primary viral infection
caused by primary parasite - leads to a weakened barrier (ex. IAV influenza A virus)
Secondary infection
opportunist parasite takes advantage and causes a severe 2ndary infection (ex. pneumonia)
intracellular pathogens
grow into cells, burst, invade…
ex. chlamydia
have ability to grow and reproduce inside of host cells
extracellular pathogens
not invading cells, just in tissues
virulence factor
a gene product that enables a pathogen to cause disease
ex. motility, attachment, enzymes, toxins
so many strategies to surviving in a host
- evading antibodies
- stopping signal transmission
tenericutes
lack cell wall! - allows for unique structure
attachment structure
pili/ fimbriae
malaria parasite virulence factor ex
apical complex that allows attachment and invasion of cells
capsules
virulence factor
targets cell for destruction - evade immune system defenses!
